I have no proven information but I once argued that we all worry too much about what we put into our stomach and pay no heed to what is still in our gut from previous meals. I thought about this since I too was getting unpredictable results from the 2 hour readings. If I stayed rigidly low carb for some days after not being strict then my BG levels got progressively lower each day for about five days. This seems a long time to retain food but that's what happens and I have repeated the experiment countless times now.
In my case it just seems that I have to think about the whole gut rather than just the stomach.